Stool



FIG. 1 is a perspective view of the design, this view showing the front and the right sides thereof;

FIG. 2 is a front view of the design;

FIG. 3 is a right side view of the design, the left side having the same appearance as the right side; and,

FIG. 4 is a top view of the design. 

The ornamental design for stool, as shown and described. 